NHS complaints procedures are designed to provide the maximum number of obstacles to a complaint progressing. Many years ago, a serious mistake by Whipps Cross hospital came very close to killing me. Naively believing that the complaints procedure would ensure the same thing couldn't happen to someone else, I followed it.
I had to be incredibly persistent as it was almost closed half a dozen times along the way. The final result was an apology and the vaguest of assurances about unspecified steps that would be taken to prevent a reoccurrence. I was left with zero confidence that anything would change, and frankly wouldn't bother next time.